1. Technical Field
The present invention relates generally to a semiconductor integrated circuit, and more particularly, to a semiconductor device.
2. Related Art
In general, a semiconductor device such as DRAM (Dynamic Random Access Memory) includes memory cells each having a transistor and a capacitor. In the memory cells having such a configuration, a leakage current occurs. Therefore, as the time passes, data stored in the memory cells are lost by the leakage current. Accordingly, the semiconductor device such as DRAM should periodically perform a refresh operation to save the data.
According to a known art, the semiconductor device uses a main word line enable signal for selecting a main word line and a sub word line driving signal for selecting a sub word line as a signal for driving a word line. When performing a refresh operation, the semiconductor device does not toggle a sub word line driving signal for driving a corresponding mat, and main word lines are sequentially recharged according to a main word line enable signal. Accordingly, according to the known art, the semiconductor device reduces a refresh current by removing a toggle current of the sub word line driving signal.
Furthermore, according to a known art, semiconductor devices include a row redundancy word line (hereafter, redundancy word line) for replacing a failed memory cell. Here, the redundancy word line may have an “any-to-any” fuse configuration. In such a case, when the sub word line driving signal is not toggled and a fuse indicating a failed memory cell coincides with a row address while a refresh operation is performed, the activated sub word line driving signal should be deactivated because the corresponding redundancy word line may exist in another mat. That is, the toggle current of the sub word line driving signal is consumed during the refresh operation.